During his 1974 campaign for the sheriff's office, Thompson and six others were arrested and charged with conspiring to murder his opponent, incumbent Sheriff C. P. "Red" Walker. The charges were dismissed by Attorney General Bill Baxley who said there was no evidence to enable prosecution. Thompson narrowly lost to Walker in the primary and later sued for false arrest, accepting an out of court settlement in 1976.

He was first elected to the County Commission in 1992. He left the Democratic Party two years later.